1. Technical Field
The present invention is directed to valves used in medical procedures, and more particularly, to a one-way valve apparatus that is structured to permit the passage of fluids in one direction only during a medical procedure, or as a consequence of a medical procedure.
2. Background Information
One-way medical valves are used in medicine for a variety of procedures involving drainage of fluids from the patient, and/or the infusion of fluids into the patient. The use of such valves is important in situations wherein the reflux or backflow of fluids can cause complications to the patient during or following a medical procedure, as well as in situations where the inflow of a fluid, such as air, can cause an unwanted and potentially harmful dilation of a particular part of a patient's anatomy.
For optimal use, it is important that such one-way valves be capable of operating in the physiological range. The valves should be capable of operating consistently at very low pressures while encountering a range of biological fluids. The valves should also be substantially unaffected by fluids and particles in the fluids, so that the valves do not stick in the closed position, thereby preventing the free flow of fluids therethrough.
One-way valves are often used in medical procedures where it is necessary to continuously drain fluid from an affected area. One especially important use for such valves is as a chest drain valve used for pneumothoraces. To be useful for chest drainage, it is important that the valve be structured to permit fluid to continuously drain through the valve. The valve must also be able to remain reliably closed when not draining fluid, in order to prevent the influx of air through the valve and into the chest cavity.
Devices for draining the chest cavity are known in the art. For example, it has been known to insert a drainage tube into the chest to establish a connection with a drainage apparatus. In order to avoid the possibility of reversal of flow of the drained fluid or the inadvertent disconnection of the drainage conduits, a relatively cumbersome drainage apparatus that included fluid traps and receptacles was positioned near the patient's bed. Although the drainage procedure with such a device was generally successful, the use of the cumbersome apparatus required that the drainage procedure not be interrupted. As a result, the patient was generally confined to the bed in order to avoid such interruption or interference with the drainage process.
An improved device for draining the chest cavity was described in U.S. Pat. No. 3,463,159 to Heimlich. This patent is incorporated by reference herein. This device is smaller than previously existing devices, and is also portable so that the patient need not be confined to a bed. The Heimlich device was formed of a generally cylindrical chamber made from a rigid plastic. The chamber houses a rubbery latex-type valve material. The valve material is open at one end to permit the entry of the fluid, and includes flattened walls at its outlet end. The flattened walls are separable to allow fluid and non-fluid particles to drain from the chest through a passage between the walls. At all other times, the walls are yieldably urged into a flattened condition to close the passage and prevent the undesired reverse flow of air and other materials into the chest cavity.
Although the Heimlich valve has a favorable overall configuration for fluid drainage, the device is still somewhat larger and more unwieldy than desired. In addition, the rubbery valve has a propensity to stick closed when biological fluids dry in the valve passage. Another problem with this and other prior art valves is that such devices are generally formulated from compounds, such as latex, which have been linked to allergic reactions in some individuals. In addition, latex valves are somewhat reactive to certain body materials, such as proteins. These materials may stick to the valve, and may cause the valve to stick in the closed position. Therefore, in order to minimize this possibility, it is often necessary to add talc to such valves. Also, since latex is a hydrophilic material, latex valves are prone to pick up water and swell. Use of a hydrophilic material runs counter to the purpose of the device, which is to provide a conduit to eliminate fluids from the system.
Another disadvantage of prior art valves, such as the valve described in Heimlich, is that the valves are frequently formed from a round tube that is pressed into a flat configuration. This arrangement generally leaves a gap at each of the edges of the mouth of the valve. These gaps may permit the unintended leakage of fluid even when the valve is closed.
What is desired is a valve that is compact, that effectively prevents the undesired backflow of fluids, that is formed from compounds which are substantially nonreactive to the fluids being drained or injected therethrough, and that minimizes the possibility of inadvertent leakage through the valve.